The present invention relates to a method and control arrangement for terminating an accidental switch on of a deep fryer apparatus when it is not filled with oil, the deep fryer apparatus comprises a vessel closed at the bottom and at the sides, and a substantially horizontally formed electric heating element being in direct contact with the oil is placed within the vessel. Deep fat fryer apparatuses in which the temperature of the oil can be raised to a required level by means of an electrically operated heating element are often used in food industry. In the method according to the invention the temperature is measured at one or more determined points of the inner space of the vessel of the deep fryer apparatus, and by observing the measured temperature value accidental switch on of the apparatus with a vessel without oil is detected and terminated at the same time.
In the field of gastronomy there are known methods in which the temperature is continuously observed, and based on the measured values certain interventions in the operation are done. Patent application HU 9700221 discloses a control unit for electronic control of gas-cookers and/or electric boiling plates and/or roasters, grillers and the like. The control unit has an EEPROM in which time and/or temperature dependent characteristic curves and/or cycle times are stored and also, it is adapted to store additional control settings modified relative to the ones stored in the EEPROM. Patent application DE 19628274 discloses a safety device in which accidental switch on of household cooking appliances or fryers is prevented by means of a decoder and an automatic voltage cut-off unit. The safety device is also applicable to switch off the cooking appliance or fryer when it is left switched on by chance. In both cases, detection of temperature takes place directly, therefore a prompt signal for performing an automatic counter-measure can not be provided for example when accidental switch on happens in a state entirely different from the proper use, for instance when there is no oil filled in the deep fryer.
With known apparatuses when they are switched on by accident without having oil filled in them, the temperature of the heating element and the neighbouring parts within the apparatus increases rapidly which usually leads to irreversible damage of the apparatus before accidental switch on is detected. To avoid this a temperature sensor is placed at one or more points within the apparatus. The signals of the sensor (s) are continuously observed and the filament current is cut off when the temperature exceeds a predetermined value. However, experience shows that only a threshold of such a value can be determined with which the damage of the apparatus is unavoidable.
The object of the present invention is to provide an apparatus and method with which the filament current can be cut off at an earlier point of time, that is, before the apparatus without oil filled in it would inevitably be damaged when it is switched on accidentally.